1. Field of the Invention
The present invention relates to management of data in a computer system and more particularly to the management of the storage of data within such a system.
2. Description of the Related Art
In a computer system, the management of the storage of data is critical to provide for the efficient movement of data in the system. The computer system includes a central processing unit (CPU) and a host storage system. In such a system, a compressor is utilized to efficiently store information in the host storage system. Sometimes, data records which pass through the compressor may result in data expansion. Occasionally, byte strings under on-the-fly compression actually expand such as where the byte strings are encrypted.
Compression of English language plain text relies upon a skewed symbol probability distribution. However, encryption confounds the symbol probability distribution by rendering it flat or uniform. Expansion or contraction of a byte string is measured at the compressor output. (The length of the compressed data is larger than the original data). Two problems arise from this expansion. The first is there may not be enough space to store the expanded data on the media. The second is that for the transmission of multiple records some of the records may expand and some of the records may compress.
Accordingly, recovery actions are required to affect the performance of the computer system which are complex. Hence, to recover the data, either the data must be retransmitted or decompressed. Both of these recovery procedures significantly increase the latency period of the computer system.
In addition, if multiple records are being transferred in a single command, then the recovery action will have to occur on each data record produced. Accordingly, what is needed is a method and apparatus which allows for the efficient movement of data in a computer system. The system should be one which assures the recording and communication of a minimal length data among a CPU and host storage system. This assurance must be accomplished without increasing the latency period of the computer system. The present invention addresses such a need.